what are some possible motives a murder might have? looking for dark and scary.

Good Afternoon Detectives!

I am in the myst of creating an outline for my murder mystery book: Westfield

The predicament I have reached is coming up with motives for my murderer Donna/Donny. In the story they fake their own death in order to kill someone on halloween 3 years later. Enough time for people to forget she/he's dead so he/she can do the dirty work of murdering people. I can't think of a reason one would do that.

I need a spark of imagination that I'm sure one of yall can help me with.

* Why would one do that?

* Who is she murdering?